Discussion of Papers Presented at the Symposlum: Optimal Conditions of the Homogeneous Nucleation of Cubic Ice (Ic) from Concentrated Solutions of LiCl •D2O.

1983 ◽  
Vol 87 (21) ◽  
pp. 4335-4335
Author(s):  
J Dupuy
Keyword(s):  
Homogeneous Nucleation ◽  
Optimal Conditions ◽  
Concentrated Solutions

On the optimal conditions for the homogeneous nucleation of cubic ice from concentrated solutions of lithium chloride-deuterium oxide

1983 ◽  
Vol 87 (21) ◽  
pp. 4170-4173 ◽  
Author(s):  
A. Elarby-Aquizerat ◽  
J. F. Jal ◽  
C. Ferradou ◽  
J. Dupuy ◽  
P. Chieux ◽  
...  
Keyword(s):  
Lithium Chloride ◽  
Homogeneous Nucleation ◽  
Deuterium Oxide ◽  
Optimal Conditions ◽  
Concentrated Solutions

Amorphous silica coating on α-alumina particles

1995 ◽  
Vol 53 ◽  
pp. 210-211
Author(s):  
J. W. Mellowes ◽  
C. M. Chun ◽  
I. A. Aksay
Keyword(s):  
Amorphous Silica ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Silica Coating ◽  
Full Density ◽  
Optimal Conditions ◽  
Fine Grained ◽  
Alumina Particles ◽  
Complete Mullitization ◽  
Powder Compacts

Mullite (3Al2O32SiO2) can be fabricated by transient viscous sintering using composite particles which consist of inner cores of a-alumina and outer coatings of amorphous silica. Powder compacts prepared with these particles are sintered to almost full density at relatively low temperatures (~1300°C) and converted to dense, fine-grained mullite at higher temperatures (>1500°C) by reaction between the alumina core and the silica coating. In order to achieve complete mullitization, optimal conditions for coating alumina particles with amorphous silica must be achieved. Formation of amorphous silica can occur in solution (homogeneous nucleation) or on the surface of alumina (heterogeneous nucleation) depending on the degree of supersaturation of the solvent in which the particles are immersed. Successful coating of silica on alumina occurs when heterogeneous nucleation is promoted and homogeneous nucleation is suppressed. Therefore, one key to successful coating is an understanding of the factors such as pH and concentration that control silica nucleation in aqueous solutions. In the current work, we use TEM to determine the optimal conditions of this processing.

scholarly journals Study of Cellulose Interaction with Concentrated Solutions of Sulfuric Acid

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Michael Ioelovich
Keyword(s):  
Sulfuric Acid ◽  
High Power ◽  
Room Temperature ◽  
Regenerated Cellulose ◽  
Structure And Properties ◽  
Optimal Conditions ◽  
Initial Sample ◽  
Concentrated Solutions ◽  
Crystallinity Degree ◽  
20 Nm

The effect of the concentration of sulfuric acid (SA) and temperature on structure and properties of cellulose (MCC) had been studied. Investigations showed that solubility of the initial sample at the room temperature increased gradually in the range of the acid concentration from 50 to 60 wt.% SA. When SA concentration reached 65 wt.%, then MCC sample dissolved completely. Cellulose regenerated from 65 wt.% SA had an amorphized structure and was characterized by high enzymatic digestibility. At increased temperature, 45°C, solubility of MCC in SA was raised, while yield and DP decreased. After treatment of MCC with hot 50–60 wt.% SA, the crystallinity degree of the obtained cellulose samples changed slightly, and these samples retained mainly the CI crystalline polymorph. However, when SA concentration reached 65 wt.%, then regenerated cellulose had CII crystalline polymorph, reduced crystallinity degree, and low DP. Using optimal conditions of the acidic treatment (57–60 wt.% SA, T = 45°C; t=1 h) in combination with the high-power disintegration permitted obtaining the CI nanocrystalline cellulose particles (NCP) having sizes 150–200 × 10–20 nm with the heightened yield (65–70%). These NCP can be used, for example, as reinforcing nanofillers for various composites.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Lattice imaging of precipitates in Al-Zn-Mg alloy

1986 ◽  
Vol 44 ◽  
pp. 412-413
Author(s):  
C. K. Wu
Keyword(s):  
Grain Boundaries ◽  
Homogeneous Nucleation ◽  
Alloy System ◽  
Mg Alloy ◽  
List Type ◽  
Lattice Structures ◽  
Type Number ◽  
Orientation Relationships ◽  
Lattice Imaging ◽  
The Matrix

The precipitation phenomenon in Al-Zn-Mg alloy is quite interesting and complicated and can be described in the following categories:(i) heterogeneous nucleation at grain boundaries;(ii) precipitate-free-zones (PFZ) adjacent to the grain boundaries;(iii) homogeneous nucleation of snherical G.P. zones, n' and n phases inside the grains. The spherical G.P. zones are coherent with the matrix, whereas the n' and n phases are incoherent. It is noticed that n' and n phases exhibit plate-like morpholoay with several orientation relationship with the matrix. The high resolution lattice imaging techninue of TEM is then applied to study precipitates in this alloy system. It reveals the characteristics of lattice structures of each phase and the orientation relationships with the matrix.

Immunocytochemical methodology for the localization of neuronal antigens at the ultrastructural level

1990 ◽  
Vol 48 (3) ◽  
pp. 876-877
Author(s):  
Jorge Pecci Saavedra ◽  
Mark Connaughton ◽  
Juan José López ◽  
Alicia Brusco
Keyword(s):  
Spinal Cord ◽  
Substantia Nigra ◽  
Polyclonal Antibodies ◽  
Ultrastructural Level ◽  
Point Of View ◽  
Nerve Tissue ◽  
Tissue Fixation ◽  
Optimal Conditions ◽  
Interpeduncular Nucleus ◽  
Technical Point

The use of antibodies as labels for the localization of specific molecules in the nervous systan has been extensively applied in recent years. Both monoand polyclonal antibodies or antisera have been employed. The knowledge of the organization of neuronal connectivities, gliovascular relationships, glioneuronal relationships and other features of nerve tissue has greatly increased.A number of areas of the nervous systan have been analyzed in our laboratory, including the nuclei of the raphe system, the reticular formation, interpeduncular nucleus, substantia nigra, caudate nucleus, putamen, pallidum, spinal cord, pineal gland and others.From a technical point of view, a number of variables needed to be taken into account in order to obtain reliable and reproducible results. The design of the optimal conditions of tissue fixation, embedding, sectioning, dilution of antibodies, and adaptation of Sternberger PAP technique were sane of the parameters taken into account to optimize the results. It is critical that each step of the technique be defined for each particular case.

Stability of antioxidant vitamins in whole human blood during overnight storage at 4°C and frozen storage up to 6 months

2018 ◽  
Vol 88 (3-4) ◽  
pp. 151-157 ◽  
Author(s):  
Scott W. Leonard ◽  
Gerd Bobe ◽  
Maret G. Traber
Keyword(s):  
Ascorbic Acid ◽  
Whole Blood ◽  
Healthy Subjects ◽  
Frozen Storage ◽  
Blood Collection ◽  
Plasma Samples ◽  
Optimal Conditions ◽  
Plasma Ascorbic Acid ◽  
Blood Samples ◽  
Sample Handling

Abstract. To determine optimal conditions for blood collection during clinical trials, where sample handling logistics might preclude prompt separation of erythrocytes from plasma, healthy subjects (n=8, 6 M/2F) were recruited and non-fasting blood samples were collected into tubes containing different anticoagulants (ethylenediaminetetra-acetic acid (EDTA), Li-heparin or Na-heparin). We hypothesized that heparin, but not EDTA, would effectively protect plasma tocopherols, ascorbic acid, and vitamin E catabolites (α- and γ-CEHC) from oxidative damage. To test this hypothesis, one set of tubes was processed immediately and plasma samples were stored at −80°C, while the other set was stored at 4°C and processed the following morning (~30 hours) and analyzed, or the samples were analyzed after 6 months of storage. Plasma ascorbic acid, as measured using HPLC with electrochemical detection (LC-ECD) decreased by 75% with overnight storage using EDTA as an anticoagulant, but was unchanged when heparin was used. Neither time prior to processing, nor anticoagulant, had any significant effects upon plasma α- or γ-tocopherols or α- or γ-CEHC concentrations. α- and γ-tocopherol concentrations remained unchanged after 6 months of storage at −80°C, when measured using either LC-ECD or LC/mass spectrometry. Thus, refrigeration of whole blood at 4°C overnight does not change plasma α- or γ-tocopherol concentrations or their catabolites. Ascorbic acid is unstable in whole blood when EDTA is used as an anticoagulant, but when whole blood is collected with heparin, it can be stored overnight and subsequently processed.

A Simple Method for Estimation of Lipoxygenase and Cyclo-Oxygenase Pathways in Human Platelets - the Use of Thiobarbituric Acid Reaction

1980 ◽  
Vol 44 (02) ◽  
pp. 111-114 ◽  
Author(s):  
Hiroshi Takayama ◽  
Minoru Okuma ◽  
Haruto Uchino
Keyword(s):  
Time Course ◽  
Normal Values ◽  
Human Platelet ◽  
Thiobarbituric Acid ◽  
Human Platelets ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Simple Method ◽  
Acid Reaction ◽  
Optimal Ph

SummaryTo develop a simple method for estimation of platelet lipoxygenase (PLO) and cyclo-oxygenase (PCO) pathways, the arachidonic acid (AA) metabolism of human platelet was investigated under various experimental conditions by the use of the thiobarbituric acid (TBA) reaction and a radioisotope technique. A TBA-reactive substance different from malondialdehyde (MDA) via PCO pathway was detected and shown to be derived from the PLO pathway. Since the optimal pH and time course of its formation were different from those of MDA formation via PCO pathway, PLO and PCO pathways were estimated by quantitating the TBA-reactive substances produced by the incubation of AA either with aspirin-treated platelets or with untreated ones, respectively, each under optimal conditions. Normal values expressed in terms of nmol MDA/108 platelets were 1.17±0.34 (M±SD, n = 31) and 0.79±0.15 (n = 31) for PLO and PCO pathways, respectively.

EXPLORATORY STUDY OF EMPLOYEE ENGAGEMENT

2020 ◽  
Vol 4 (2) ◽  
pp. 102-106
Author(s):  
Tita Miawati ◽  
Widodo Sunaryo ◽  
Nancy Yusnita
Keyword(s):  
Employee Engagement ◽  
Exploratory Study ◽  
Research Method ◽  
Turnover Rate ◽  
Group Discussion ◽  
Multinational Company ◽  
Optimal Conditions ◽  
Implementation Program ◽  
Employee Groups ◽  
Company Growth

Employee engagement is now recognized as an important topic in the company because it relates with turnover rate, productivity of employee and finally to the company growth. A study conducted to describe the finding of an effort to increase the effectiveness of engagement implementation by company in order to increase level of employee engagement. The study used qualitative research method through exploratory study in a multinational company in Jakarta. Data obtained through interviews with key leaders of the company to find out how the implementation of engagement conducted by the company, and a Focus Group Discussion of employee groups to determine the condition of employee engagement. The researchers analyzed the data from both of company and employees to see if there is a gap between engagement implementation by the company and the conditions of employee engagement. To obtain the validity of the data, researchers used triangulation techniques carried out by experts in the HR field. The study found that the company's efforts to implement employee engagement had not been carried out optimally and equally on all engagement indicators. Likewise, the condition of employee engagement has not yet reached optimal conditions. The conclusion described that there is a gap between company’s engagement implementation program and the engagement conditions felt by employees. Thus, it is necessary to make efforts to improve the effectiveness of engagement implementation so that increasing the employee engagement bring contributes to the company's growth

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